What is the term for a long-standing right allowing one property owner to cross another's property?

The concept being described is an easement, which is a legal right allowing one party to use the property of another for a specific purpose. The correct term is "easement appurtenant." An easement appurtenant benefits a particular piece of land (the dominant tenement) and allows its owner to access or cross the land of another (the servient tenement). This type of easement is typically permanent and transfers with the property when sold or conveyed, which highlights its long-standing nature.

In contrast, a prescriptive easement arises from continuous use of another's property over a period of time, with certain conditions that may vary by jurisdiction, but it doesn’t require the easement to belong to a specific dominant land. A general easement is not a recognized legal term in real estate; rather, easements are typically categorized more specifically. Lastly, access rights could refer to a more general concept of rights to enter or use land, but it does not specifically convey the legal implications or permanence associated with an easement appurtenant. Thus, the authoritative nature and specificity of an easement appurtenant make it the appropriate choice in this context.